FCOM-5 is agressively pushing Hainan in every thread....
Although Hainan does offer one month on and one month off....be careful for caveats...often the airline requires you to complete recurrent training, medicals and visa renewals in China during your regular vacation schedule. The contracts change yearly and verbal promises are almost never honored.
One of the plus sides of commuting is you will rack up massive frequent flyer miles and can use those for upgrades, free positive space tickets during vacation, etc. Just pick a good airline and stick to them.